/***************************************************************************
 * Copyright (c) 2024 Microsoft Corporation 
 * 
 * This program and the accompanying materials are made available under the
 * terms of the MIT License which is available at
 * https://opensource.org/licenses/MIT.
 * 
 * SPDX-License-Identifier: MIT
 **************************************************************************/


/**************************************************************************/
/**************************************************************************/
/**                                                                       */
/** ThreadX Component                                                     */
/**                                                                       */
/**   Thread                                                              */
/**                                                                       */
/**************************************************************************/
/**************************************************************************/


/* #define TX_SOURCE_CODE  */


/* Include necessary system files.  */

/* #include "tx_api.h" */
/* #include "tx_thread.h" */
/* #include "tx_timer.h" */


    .global     _tx_thread_execute_ptr
    .global     _tx_thread_current_ptr
    .global     _tx_timer_time_slice
#ifdef TX_ENABLE_EXECUTION_CHANGE_NOTIFY
    .global     _tx_execution_thread_enter
#endif

    .arm
    .text
    .eabi_attribute Tag_ABI_align_preserved, 1
/**************************************************************************/
/*                                                                        */
/*  FUNCTION                                               RELEASE        */
/*                                                                        */
/*    _tx_thread_schedule                               Cortex-R4/AC6     */
/*                                                           6.1          */
/*  AUTHOR                                                                */
/*                                                                        */
/*    William E. Lamie, Microsoft Corporation                             */
/*                                                                        */
/*  DESCRIPTION                                                           */
/*                                                                        */
/*    This function waits for a thread control block pointer to appear in */
/*    the _tx_thread_execute_ptr variable.  Once a thread pointer appears */
/*    in the variable, the corresponding thread is resumed.               */
/*                                                                        */
/*  INPUT                                                                 */
/*                                                                        */
/*    None                                                                */
/*                                                                        */
/*  OUTPUT                                                                */
/*                                                                        */
/*    None                                                                */
/*                                                                        */
/*  CALLS                                                                 */
/*                                                                        */
/*    None                                                                */
/*                                                                        */
/*  CALLED BY                                                             */
/*                                                                        */
/*    _tx_initialize_kernel_enter          ThreadX entry function         */
/*    _tx_thread_system_return             Return to system from thread   */
/*    _tx_thread_context_restore           Restore thread's context       */
/*                                                                        */
/*  RELEASE HISTORY                                                       */
/*                                                                        */
/*    DATE              NAME                      DESCRIPTION             */
/*                                                                        */
/*  09-30-2020     William E. Lamie         Initial Version 6.1           */
/*                                                                        */
/**************************************************************************/
/* VOID   _tx_thread_schedule(VOID) */
/* { */
    .global _tx_thread_schedule
    .type   _tx_thread_schedule, "function"
_tx_thread_schedule:

    /* Enable interrupts.  */

#ifdef TX_ENABLE_FIQ_SUPPORT
    CPSIE   if                                  // Enable IRQ and FIQ interrupts
#else
    CPSIE   i                                   // Enable IRQ interrupts
#endif

    /* Wait for a thread to execute.  */
    /* do */
    /* { */
    LDR     r1, =_tx_thread_execute_ptr         // Address of thread execute ptr

__tx_thread_schedule_loop:

    LDR     r0, [r1, #0]                        // Pickup next thread to execute
    CMP     r0, #0                              // Is it NULL?
    BEQ     __tx_thread_schedule_loop           // If so, keep looking for a thread

    /* } */
    /* while(_tx_thread_execute_ptr == TX_NULL); */

    /* Yes! We have a thread to execute.  Lockout interrupts and
       transfer control to it.  */

#ifdef TX_ENABLE_FIQ_SUPPORT
    CPSID   if                                  // Disable IRQ and FIQ interrupts
#else
    CPSID   i                                   // Disable IRQ interrupts
#endif

    /* Setup the current thread pointer.  */
    /* _tx_thread_current_ptr =  _tx_thread_execute_ptr; */

    LDR     r1, =_tx_thread_current_ptr         // Pickup address of current thread
    STR     r0, [r1, #0]                        // Setup current thread pointer

    /* Increment the run count for this thread.  */
    /* _tx_thread_current_ptr -> tx_thread_run_count++; */

    LDR     r2, [r0, #4]                        // Pickup run counter
    LDR     r3, [r0, #24]                       // Pickup time-slice for this thread
    ADD     r2, r2, #1                          // Increment thread run-counter
    STR     r2, [r0, #4]                        // Store the new run counter

    /* Setup time-slice, if present.  */
    /* _tx_timer_time_slice =  _tx_thread_current_ptr -> tx_thread_time_slice; */

    LDR     r2, =_tx_timer_time_slice           // Pickup address of time slice
                                                //   variable
    LDR     sp, [r0, #8]                        // Switch stack pointers
    STR     r3, [r2, #0]                        // Setup time-slice

#ifdef TX_ENABLE_EXECUTION_CHANGE_NOTIFY

    /* Call the thread entry function to indicate the thread is executing.  */

    MOV     r5, r0                              // Save r0
    BL      _tx_execution_thread_enter          // Call the thread execution enter function
    MOV     r0, r5                              // Restore r0
#endif

    /* Switch to the thread's stack.  */
    /* sp =  _tx_thread_execute_ptr -> tx_thread_stack_ptr; */

    /* Determine if an interrupt frame or a synchronous task suspension frame
       is present.  */

    LDMIA   sp!, {r4, r5}                       // Pickup the stack type and saved CPSR
    CMP     r4, #0                              // Check for synchronous context switch
    BEQ     _tx_solicited_return
    MSR     SPSR_cxsf, r5                       // Setup SPSR for return
#ifdef __ARM_FP
    LDR     r1, [r0, #144]                      // Pickup the VFP enabled flag
    CMP     r1, #0                              // Is the VFP enabled?
    BEQ     _tx_skip_interrupt_vfp_restore      // No, skip VFP interrupt restore
    VLDMIA  sp!, {D0-D15}                       // Recover D0-D15
    LDR     r4, [sp], #4                        // Pickup FPSCR
    VMSR    FPSCR, r4                           // Restore FPSCR
_tx_skip_interrupt_vfp_restore:
#endif
    LDMIA   sp!, {r0-r12, lr, pc}^              // Return to point of thread interrupt

_tx_solicited_return:

#ifdef __ARM_FP
    LDR     r1, [r0, #144]                      // Pickup the VFP enabled flag
    CMP     r1, #0                              // Is the VFP enabled?
    BEQ     _tx_skip_solicited_vfp_restore      // No, skip VFP solicited restore
    VLDMIA  sp!, {D8-D15}                       // Recover D8-D15
    LDR     r4, [sp], #4                        // Pickup FPSCR
    VMSR    FPSCR, r4                           // Restore FPSCR
_tx_skip_solicited_vfp_restore:
#endif
    MSR     CPSR_cxsf, r5                       // Recover CPSR
    LDMIA   sp!, {r4-r11, lr}                   // Return to thread synchronously
    BX      lr                                  // Return to caller

/* } */


#ifdef __ARM_FP
    .global tx_thread_vfp_enable
    .type   tx_thread_vfp_enable, "function"
tx_thread_vfp_enable:
    MRS     r2, CPSR                            // Pickup the CPSR
#ifdef TX_ENABLE_FIQ_SUPPORT
    CPSID   if                                  // Disable IRQ and FIQ interrupts
#else
    CPSID   i                                   // Disable IRQ interrupts
#endif
    LDR     r0, =_tx_thread_current_ptr         // Build current thread pointer address
    LDR     r1, [r0]                            // Pickup current thread pointer
    CMP     r1, #0                              // Check for NULL thread pointer
    BEQ     __tx_no_thread_to_enable            // If NULL, skip VFP enable
    MOV     r0, #1                              // Build enable value
    STR     r0, [r1, #144]                      // Set the VFP enable flag (tx_thread_vfp_enable field in TX_THREAD)
__tx_no_thread_to_enable:
    MSR     CPSR_cxsf, r2                       // Recover CPSR
    BX      LR                                  // Return to caller

    .global tx_thread_vfp_disable
    .type   tx_thread_vfp_disable, "function"
tx_thread_vfp_disable:
    MRS     r2, CPSR                            // Pickup the CPSR
#ifdef TX_ENABLE_FIQ_SUPPORT
    CPSID   if                                  // Disable IRQ and FIQ interrupts
#else
    CPSID   i                                   // Disable IRQ interrupts
#endif
    LDR     r0, =_tx_thread_current_ptr         // Build current thread pointer address
    LDR     r1, [r0]                            // Pickup current thread pointer
    CMP     r1, #0                              // Check for NULL thread pointer
    BEQ     __tx_no_thread_to_disable           // If NULL, skip VFP disable
    MOV     r0, #0                              // Build disable value
    STR     r0, [r1, #144]                      // Clear the VFP enable flag (tx_thread_vfp_enable field in TX_THREAD)
__tx_no_thread_to_disable:
    MSR     CPSR_cxsf, r2                       // Recover CPSR
    BX      LR                                  // Return to caller
#endif
